The gastrointestinal tract, also called the alimentary canal, is a long tube through which food is taken into the body and digested. The alimentary canal begins at the mouth, and includes the pharynx, esophagus, stomach, small and large intestines, and rectum. In human beings, this passage is about 30 feet (9 meters) long.
Small, ring-like muscles, called sphincters, surround portions of the alimentary canal. In a healthy person, these muscles contract or tighten in a coordinated fashion during eating and the ensuing digestive process, to temporarily close off one region of the alimentary canal from another region of the alimentary canal.
In the rectum, two muscular rings, called the internal and external sphincter muscles, normally keep fecal material from leaving the anal canal. The external sphincter muscle is a voluntary muscle, and the internal sphincter muscle is an involuntary muscle. Together, by voluntary and involuntary action, these muscles normally contract to keep fecal material in the anal canal.
The rectum can stretch and hold fecal material for some time after a person becomes aware that the material is there. The holding action of these sphincter muscles is critical in maintaining fecal continence.
Damage to the external or internal sphincter muscles can cause these sphincters to dysfunction or otherwise lose their tone, such that they can no longer sustain the essential fecal holding action. Fecal incontinence results, as fecal material can descend through the anal canal without warning, stimulating the sudden urge to defecate.
The recurring sensation of uncontrolled fecal urgency alone can produce significant, negative impact on lifestyle. The physical effects of fecal incontinence (i.e., the loss of normal control of the bowels and gas, liquid, and solid stool leakage from the rectum at unexpected times) can also cause embarrassment, shame, and a loss of confidence, and can further lead to mental depression.
Fecal incontinence affects as many as one million Americans. It is more common in women and in the elderly of both sexes. Many people with fecal incontinence are ashamed to talk about their problem with their doctor or family.
In women, damage to the external or internal sphincter muscle can occur during childbirth. It is especially likely to happen in a difficult delivery that uses forceps and/or an episiotomy. Muscle damage can also occur as a result of trauma, or during rectal surgery. It may also occur in people with inflammatory bowel disease or an abscess in the perirectal area.
Young people suffering damage to these sphincters in the rectum can often compensate for the muscle weakness to avoid incontinence. However, they typically develop incontinence in later life, as their muscles grow weaker and the supporting structures in the pelvis become loose.
There are non-surgical ways to treat fecal incontinence. For example, dietary bulking agents or other antimotility agents (like fats) can be used to change the texture of fecal material, to slow its descent through the rectum. Biofeedback therapy has met with success. Still, this therapy is time consuming and works to overcome dysfunction only of the voluntary external sphincter muscle. Biofeedback therapy is not effective in overcoming dysfunction of the involuntary internal sphincter muscle.
There are also various surgical options for treating fecal incontinence. These surgical options include, for example, Parks post-anal repair, encirclement (using Tiersch wire or gracilis muscle), overlapping sphincteroplasty and levatoroplasty, gluteus muscle transposition, colostomy, gracilis muscle stimulated neosphinter, and artificial bowel sphincters.
Other abnormal, uncomfortable or debilitating conditions can occur in the rectum and adjoining intestines, which require treatment or surgical intervention. For example, cancer often arises in polyps, small noncancerous growths in the intestine. A tendency to develop polyps is probably influenced by genes. Regardless, it is a common practice to remove polyps, when discovered.
Many people also suffer hemorrhoids, or piles. Hemorrhoids are enlargements of the veins of the rectum. Many people seem to inherit a tendency toward developing hemorrhoids. However, any condition that causes prolonged or repeated increases in the blood pressure in the rectal veins may contribute to the development of hemorrhoids. Such conditions include constipation, pregnancy, and long periods of standing. Hemorrhoids can be internal (protruding through the anal sphincter) or external (covered with skin outside the sphincter). Hemorrhoids of the external veins usually cause little discomfort, unless a blood clot forms in the affected vein and results in inflammation. Hemorrhoids of the internal veins may bleed or descend through the anus as a result of bowel movements. Such hemorrhoids may cause pain or itching. Mild cases can be treated with medicated ointments or suppositories (inserted capsules), or by soaking in warm water. If the victim repeatedly suffers painful attacks or bleeding, a physician may remove the hemorrhoids surgically. However, surgery for hemorrhoids can itself damage the external or internal sphincter muscle and lead to fecal incontinence.